This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. pilot, does-escalation study using microdialysis to assess changes in intracerebral cytokine levels after administration of temsirolimus and temozolomide in patients with primary or metastatic brain tumors. Both of these chemotherapy drugs have shown activity against brain tumors in laboratory and animal studies. The purpose of this study is to evaluate the feasibility of using a microdialysis catheter in determining how much temsirolimus and temozolomide remain in the brain over a period of time and the effects these drugs have on various biological substances associated with brain tumors over time. Additionally, this study will focus on whether the amount of temsirolimus in the brain changes when given in combination with temozolomide.